High-melting polymer compositions comprising a 3-methyl-1-butene polymer and another polyolefin



United States Patent HIGH-MELTING POLYMER COMPOSITIONS COM- PRISING A3-METHYL-1-BUTENE POLYMER AND ANOTHER POLYOLEFlN Walter J. Polestak,Summit, and Herbert W. Keuchel, Long Valley, N.J., assignors to CelaneseCorporation, New York, N.Y., a corporation of Delaware No Drawing. FiledNov. 2, 1966, Ser. No. 591,453

Int. Cl. C08f 29/12 US. Cl. 260896 4 Claims ABSTRACT OF THE DISCLOSURECompositions of matter comprising a major amount of a 3-methyl-l-butenepolymer blended with a minor but plasticizing amount of a poly-l-olefincapable of reducing melt flow and extrusion temperature properties ofthe 3-methyl-l-butene polymer and of increasing the tensile strengthretention value at an elevated temperature of fibers spun from thepolymer blend as compared with similar fibers spun without thepoly-l-olefin modifier.

This invention relates broadly to the art of producing high-melting,hydrocarbon polymer compositions; and, more particularly, to polymerblends that are extrudable, e.g., spinnable, and that have improvedproperties (including improved melt-flow behavior) as compared with thatof the primary component thereof.

Still more particularly the invention is concerned with means forimproving the spinning and other useful characteristics of fiber-forming(fiber-formable), high-melting, branched-chain poly-l-olefins,specifically homopolymers and copolymers of 3-methyl-l-butene (3MB),whereby there is obtained a material improvement in such properties asspinning behavior and fiber-strength retension at elevated temperatures,as well as other improvements in the useful properties of the polymer(i.e.,

both homopolymer and copolymers) in fiber, film, sheet, ribbon, tape,rod, bar, or other form.

In extruding, as in spinning, high-melting poly-l-olefins it has beenfound that fibers melt-spun from such poly-l-olefins as homopolymericand copolymeric 3- methyl-l-butene and the like do not retain theirtensile properties at elevated temperatures, even at such moderatetemperatures as 50-100 C. The usual experience with fibers of suchpolymers has been that, even though the filamentary material ischaracterized by initially high tensile-strength values at ambienttemperature (20- 30 0.), its tensile strength decreases markedly (i.e.,it shows poor tensile-strength retention) when subjected to elevatedtemperatures.

The present invention is based on our discovery that the aforementioneddeterioration in strength values of fibers of homopolymers andcopolymers of 3MB under heat can be obviated or minimized by blending amajor amount by weight of the 3MB polymer with a minor amount by weight,more particularly a minor but plasticizing amount, of a poly-l-olefinmodifier, specifically plasticizer. Such an olefinic modifier should becapable of reducing the melt flow or apparent melt viscosity of the 3MBpolymer as evidenced by actual determinations or by the lowertemperature at which the modified polymer can be extruded through anorifice such as a spinning orifice. It is also desirable that theolefinic modifier have an inherent viscosity (I.V.) in Decalin(decahydronaphthalene) at 135 C. of from about 1.0 to about 3.2, moreparticularly from 1.8 to 2.2, and still more particularly about 2.Examples of such poly-l-olefin modifiers are ice polypropylene having,for instance, an I.V. of 1.96 in Decalin at C. andpoly-(4-methyl-1-pentene) having an I.V. of 2.04 in Decalin at 135 C.Other examples include polyethylene, isotactic polystyrene,polyvinylcyclohexane, and 3MB polymer having a high-melt index, e.g.,above 80.

When such blended olefinic polymers are melt-spun, fibers are obtainedthat show an unexpectedly and unobvi ously improved retention oftenacity at elevated temperatures and which is far greater than might beexpected from the known properties of the individual primary andmodifying polymers. In other words, the polyl-olefin modifier has thecapability of increasing the tensile-strength retention value at anelevated temperature of fibers spun from the blend of polymers abovethat of fibers similarly spun from the unmodified 3MB homopolymer orcopolymer. Additionally, the extrusion of the blended polymers to yieldfibers can be effected at lower temperatures, e.g., at from 10 to 50 C.lower, than is normally required for spinning the unmodified 3MBpolymer.

The olefinic polymers constituting the components of the blends of thisinvention are prepared by known stereospecific or coordination catalyticpolymerization of the corresponding monomer or mixtures of monomers inmaking the olefinic homopolymer and copolymers, respectively. Suchcatalysts and their use in the production of copolymers (including somecopolymers that are useful in practicing this invention) are given inthe copending application of Charles L. Smart, Dagobert E. Stuetz andManuel Slovinsky, Ser. No. 399,091, filed Sept. 24, 1964, assigned tothe same assignee as the present invention and which, by thiscross-reference, is made part of the disclosure of the instantapplication.

The major (more than 50 weight percent) component of the polymeric blendcomprising the compositions of matter of this invention is a polymer ofthe group consisting of (a) homopolymeric 3-methyl-l-butene and (b)copolymers obtained by copolymerizing a major molar amount (more than 50mole percent) of 3-methyll-butene and a minor molar amount of at leastone other monoethylenically unsaturated hydrocarbon containing at least2 carbon atoms. The latter is preferably a straight-chain l-alkenecontaining from 2 through 26 carbon atoms, and still more preferably onethat contains from 7 or 8 through 20 carbon atoms. To name specificallysome monomers that are useful for copolymerization with3-methyl-1-butene one may mention ethylene, propylene, l-butene,l-hexane, l-heptene, l-octene, l-nonene, l-decene, l-tetradecene,l-hexadecene, l-octadecene, and l-eicosene, especially the normalisomers. Other examples include 4-methyl-1-pentene and styrene. Thenormal or straight-chain l-alkenes are preferred.

It is not essential that the l-alkene comonomer be a single monomerhaving a definite number of carbon atoms within the specified ranges.For example, it may be commercial or pilot-plant fractions comprised ofspecies containing a number of carbon atoms that is lower and/or higherthan that which is Within the specified ranges of carbon atoms so longas the average number of carbon atoms is within the prescribed range.Thus, the comonomer may be a commercial fraction of, for example,straight-chain l-alkenes containing from 10 to 20 carbon atoms with anaverage of 15 carbon atoms. It is preferred to keep fractions ofl-alkenes of the kind just described within a relatively narrow range ofminimum and maximum carbon contents of the individual species thereinand which is economically consistent with the practical copolymerizationresults desired.

The l-alkene or aryl-substituted l-alkene (e.g., styrene) comonomer isused in a minor molar amount (less than 50 molar percent) with respectto the total molar amount of 3-methyl-1-butene and l-alkene in themixture of monomers. Generally the l-alkene comonomer is employed in anamount ranging from 0.5 to about 20 mole percent, preferably from 0.5 tomole percent, and still more preferably from 0.5 to 7 mole percent ofthe total monomers employed in making the copolymer. The final copolymerthen may contain from 0.5 to about 20 mole percent (or 0.5-10 molepercent; or 0.5-7 mole percent) of copolymerized l-alkene, moreparticularly straightchain l-alkene, based on the total copolymer.Numerous examples of such straight-chain l-alkenes have previously beengiven.

As indicated hereinbefore, the 3MB homopolymer or copolymer (or mixturesthereof in any proportions as desired or as may be required) constitutesmore than 50 weight percent of the blend of polymers and thepoly-lolefin modifier constitutes the remainder. Preferably thepoly-l-olefin component constitutes from 2 to about 35, and still morepreferably from about 5 to about 30, weight percent of the blendedpolymers. In most cases no particular advantage seems to accrue fromusing more than about 20 weight percent of the olefinic modifier, basedon the total polymer content.

Any suitable method may be employed in blending the polymers together.For example, the polymers may be milled together on hot rolls to formsheets of homogeneous composition, which are then broken up and eitherpowdered or pelletized as may be desired. For many applications,however, the components may be preblended shortly before they arefabricated. Another technique is to feed the individual polymers intothe processing equipment thereby permitting mixing in the melt phase.This latter method is particularly advantageous in extrusion operationswhere a screw-type melt conveyor provides 4 truded on a micro-meltconstant-pressure extruder activated by a hydraulic air cylinder.Samples of monofilament collected during an individual run representedchanges in spinning temperature, pressure (throughput rates) and take-upspeed (spin drawdown).

The term, melt index, used in characterizing the 3MB polymer, is theweight in milligrams/ minute of polymer extruded through an orifice of0.1016 cm. diameter under a weight of 2160 grams at 330 C. The flowcurve thus obtained, as a function of time, was extrapolated to zerotime, and the value obtained is defined as the melt index. A single-holespinneret having a capillary diameter of 20 mils and an L/D ratio of 5was used in all the individual runs. (The L/D ratio refers to the lengthand diameter of the capillary.) The countersink angle for the spinneretwas 60.

The high-temperature testing of the filaments was carried out in a watersystem at a temperature of 95 C. Data obtained from testing in hot waterat 95 C. and in an oven at 100 C. indicated no significant diiferencebetween the two tests. The complete moisture insensitivity of thesepolyolefin fibers permitted more rapid testing in hot water withoutaifecting the results.

EXAMPLE 1 This example illustrates the results obtained in meltspinning(a) a copolymer (melt index=1.5) of 3-methyll-butene containing about4.8 mole percent of l-octene and with which copolymer there had beenadmixed, as a stabilizer, 0.3% by meight thereof of1-phenyl-4-cyclohexylphenylenediamine; and (b) a blend of this copolymerwith 5% by weight of polypropylene based on the weight of the blend.

The spinning data and characteristics of the filaments are summarized inTable 1.

TABLE I Tensile properties Take-u 95 0; Spinning s as Elongz' Tom, tom;Copolymer condition temp., C. mjinln; Denier percent g./d. g./d x

350 1, 550 0. 7 36 6. 4 1. 2 Original powder- 350 I 325 0. 5 38 5. 7 1.9 340 660 0.6 38 6.9 1.4 a a 1 bl dd ith5'7b iht m1 mixtur 1 1 1 i Powere co 0 er en e w we 0 e e o 0 r0 ene-.-

p m y g P W N 330 450 2.1 34 6.4 3.2

These are dry tenacity values at 23 C;

adequate mixing of the components. Still another method of blending thepolymers is to dissolve the individual polymers in a common organicsolvent, e.g., chlorinated hydrocarbons with boiling points above 200 C.including trichlorobenzene and Arochlor 1248, and separating the blendfrom the solution by any suitable means, e.g., by adding a liquid whichis a non-solvent for the polymer but which is miscible with the mutualpolymer solvent that is employed.

In order that those skilled in the art may better understand how thepresent invention can be carried into effect, the following examples aregiven by way of illustration and not by way of limitation. All parts andpercentages are by weight unless otherwise stated.

The polymeric blends used in the examples were prepared by physicallyadmixing powders of the individual polymers until a homogeneousadmixture had been obtained. In the case of polypropylene (I.V.=1.96 inDecalin at 135 C.), which was commercially available in the form ofpellets, the pellets were powdered by means of a Mikro pulverizer beforeadmixture with the 3MB polymer.

In carrying out the spinning tests described in the examples thepolymeric blend, formed into rods, was ex- The data in Table I show thebeneficial effects attained when a low-melt-index 3MB/1-octene copolymeris blended with 5% by weight thereof of polypropylene, and the resultingblend is then melt-spun to form a filament. It will be noted thatimprovements result both with respect to the lower temperature ofextrusion of the blend and the C. tenacity values as compared with thedata for the unmodified copolymer.

EXAMPLE 2 This example illustrates the results obtained in meltspinninga copolymer (melt index of the pelleted copolymer equals 1.6) of 3MBcontaining about 1.5 mole percent of l-hexadecene and with whichcopolymer there had been admixed 0.5%, by weight thereof, of9,10-dihydroanthracene as a stabilizer. Comparisons were made inmelt-spinning this unmodified BMB/I-hexadecene copolymer in both powderform and in pelleted form; and, also, the powder form and the pulverizedpelleted form of the aforesaid copolymer each blended with 5%, by weightof the mixture, of polypropylene. The results are summarized in Table H.

TABLE II Tensile properties Take-up 95C. Spinning speed Elong, Ten ten.,Copolymer condition temp., C. m./rnin Denier percent g./d. g/d.

40 20 1. 9 3 2.4 o na powder (Ml-= 1 2 1, 2 2 g: L 9 2 22 Blended with 5ol r0 ene 77 5. 8 8 p yp Dy 330 635 2.9 36 5. 5 3. 6 340 345 0. 7 34 5.7 3. 2 Pellets (M.I.=1.6) 350 635 1.6 35 5.7 3.0

5 6. 8 3. Pulverized pellets blended with 5% polypropylene 320 845 1. 636 6. 7 3' 4 These are dry tenacity values at 23 C.

The data in Table II show the beneficial action that results fromincorporating a small amount of polypropylene in a SMB/l-hexadecenecopolymer in powder form originally and in pulverized pellet form. Itwill be noted that the reduction of the spinning temperature whenspinning the modified copolymer was accompanied by an improvement in theelevated-temperature (95 C.) retention of fiber strength.

EXAMPLE 3 spun into filaments using a spinning temperature within therange of, for example, from about 290 C. to about 370 C., spinningorifices having diameters within the range of, for instance, from about10 mls to about 80 mils and length/ diameter ratios within the range offrom about 1 to about 20; and take-up speeds within the range of, forexample, from about 100 to about 3000 meters/minute.

Filaments spun from the blends of polymers of this invention aresuitable for use in a Wide variety of applications. For example, theycan be used in the manufacture of Woven and knitted fabrics employed inapparent and industrial products such as, for instance, filter cloths,cordage, fishing nets, covers for outdoor and other fumiture, and manyother applications, especially those where a high resistance to moistureis desirable.

Films and sheets extruded from the polymeric blends of the instantinvention are suitable for various covering and wrapping applications,e.g., wrapping and packaging of foods (both fresh and frozen);protective coverings for outdoor equipment; wrappings for undergroundpipe, cables, and the like; various miscellaneous household uses, e.g.,as shower curtains; and numerous other uses TAB LE III Tensileproperties Take-up 95 C Spinning speed, Elong., Ten., ten., copolymercondition temp., C. n1./m1n. Denier percent g./d.' g./d.

, 350 I 1,125 0. 9 35 3. 4 1.8 Original powde 360 1, 450 o. 7 35 3. s 2.3 Powdered copolymer blended with 5% y Weig of p yp p 1 33g Powderedcopolymer blended with 25% y W igh of P yp p gig 1, 2:2 3:3 330 645 1. 735 5. 2 3. 4 I 330 920 1. 2 36 6. 4 4. O Powdered copolymer blended with5% by weight of poly-(4-methyl-l-pentaue) 340 1, 295 0. 8 35 5. 3 3. 2340 1, 190 1. 3 36 6. 5 4. 0 340 1, 150 1. 2 35 6.2 3. 9

These are dry tenacity values at 43 C.

The data in Table 111 show the beneficial effect of adding two differentpoly-l-olefin modifiers to a 3MB/lhexadecene copolymer having a lowermelt index (higher molecular weight) than that used in Example 2. Moreparticularly, the addition of the polypropylene and poly(4-methyl-l-pentene) modifiers to this copolymer also permittedmelt-spinning to be carried out at a lower temperature than with theunmodified copolymer, and provided improved tensile-strength retentionof the fiber when subjected to an elevated temperature. Increasing thepolypropylene content of the blend from 5 to 25% by weight of thecopolymer decreased that initial spinning temperature without providing95 C. tenacity improvements sutficient to warrant the use of theadditional amount of polypropylene.

The results are similar to those described in Examples 1, 2, and 3 whenhomopolymeric 3-methyl-1-butene is substituted for the particular3-methy1-1-butene copoly mers employed in these examples.

The polymeric blends of this invention may be meltthat will be apparentfrom the foregoing illustrative examples.

The method of the present invention is applicable to homopolymeric andeopolymeric 3-methyl-l-butenes having an initial melt index (M.I.) levelwithin the range of from 0.5 to 80, and which may or may not have beenthermally degraded prior to extrusion. Thus it is applicable tolow-melt-index (high-molecular-weight) homopolymeric and copolymeric3-methyl-l-butenes that have been thermally degraded, prior to extrusionin fiber or other form, in order to improve their tensile properties,both at ambient and elevated temperatures, as compared with the samepolymers that have not been given such a thermal degradation treatment.When such thermally degraded polymers are used in practicing thisinvention, they can be extruded at a lower temperature than when nopolymeric modifier of the kind used in this invention has beenincorporated therein.

It will be understood, of course, by those skilled in the art that thedetailed description given hereinbefore is merely by way ofillustration, and that many variations may be made therein withoutdeparting from the spirit of our invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A composition of matter comprising a blend of a major amount byweight of (A) a polymer of the group consisting of (a) homopolymeric3-methy1-1-butene and (b) copolymers obtained by copolymerizing a majormolar amount of 3-methyl-1-butene and a minor molar amount of at leastone other monoethylenically unsaturated hydrocarbon containing at least2 carbon atoms, said polymer having a melt index in the range of about0.5 to 80; and a minor but plasticizing amount by weight of (B) apoly-(4-methy1-1-pentene) in an amount ranging from 2 to about 35 Weightpercent of the blend of polymers (A) and (B) capable of reducing theinitial extrusion temperature and the melt flow of the polymer of (A)and of increasing the tensile strength retention value at an elevatedtemperature of fibers spun from the blend of polymers above that offibers similarly spun from the polymer of (A) alone, saidpoly-(4-methyl-1-pentene) having an inherent viscosity indecahydronaphthalene at 135 C. in the range of about 1.0 to 3.2.

2. The composition of claim 1 wherein the polymer of (A) is a copolymerobtained by copolymerizing a major molar amount of 3-methyl-1-butene anda minor molar amount of a straight-chain l-alkene containing from 2through 26 carbon atoms, wherein the straight-chain 1- alkene of (A)constitutes from 0.5 to 10 mole percent of the total molar amount of thecopolymer of (A) and the poly-l-olefin of (B) ispoly-(4-methyl-1-pentene) in an amount ranging from about 5 to about 30weight percent of the blend of polymers of (A) and (B).

3. A composition as in claim 2 wherein the straightchain l-alkenecomponent of the copolymer of (A) is hexadecene, said hexadeceneconstituting from 0.5 to 10 mole percent of the total molar amount ofthe copolymer of (A), and the poly-l-ole of (B) is poly-(4-methyl-1-pentene) having an inherent viscosity in decahydronaphthalene at C.within the range of from about 1.8 to about 2.2 and constitutes fromabout 5 to about 30 weight percent of the blend of polymers of (A) and(B).

4. The composition of claim 2 in the form of filamentary material.

References Cited UNITED STATES PATENTS 3,121,070 2/1964 Coover et al260-455 MURRAY TILLMAN, Primary Examiner C. J. SECCURO, AssistantExaminer US. 01. X.R. 260-897; 264211

